Noninflammable wood chipboard - made by impregnating chips with magnesium chloride soln., then adding magnesium oxide and epsom salts

摘要

Noninflammable wood chipboard is made by impregnating the individual wood chips with an aq. soln. of MgCl2, with the simultaneous addn, of MgO obtd. by the caustic roasting of magnesite. Crystalline Epsom salts are then added to the mixt., followed by moulding into panels which are hardened at >100 degrees C. Prior to impregnation, the wood chips are pref. dried to 10% moisture, esp. to within 3% of the dry kiln wt. The amt. of water in the soln. is pef. below that which would saturate the chips or fibres. The ratio between MgO:dry MgCl2 is pref. >=2:1; and MgO+ CaO obtd. by roasting dolomite may be used instead of MgO. Hardening is pref. at 150-250 degrees C., using pressure, and a hardening time of 15-40 seconds pr mm panel thickness. The conventional process employs slow drying at 50-60 degrees C; the prod. corrodes the mfg. plan and tools used in machining the boards; and the conventional prod. is also hygroscopic. The invention eliminates these disadvantages, and permits a high proportion of wood chips to be used.